It is well known to provide ventilation to enclosed spaces of buildings, such as crawl spaces and basements, by the use of ventilators located in suitable openings of the foundation enclosure walls. Such ventilators are generally provided with adjustable closure means, such as shutters or louvers, to control the flow of air to and from the enclosed space, depending on temperature, weather conditions or seasonal changes. Generally such foundation wall ventilators are secured in the wall opening during construction of the foundation wall by cement, mortar, or other fastening materials.
It is also known to provide temperature responsive control of the closure shutters or louvers of such ventilators by the use of a bimetallic temperature responsive spring which may be operatively connected between the fixed housing of the ventilator and the movable shutters in such a way that expansion or contraction of the spring due to temperature changes causes pivotal movement of the shutters from open to closed positions in the air flow passageway through the ventilator housing. Typical of such devices are disclosed in the following patents: French Pat. No. 1,377,998 U.S. Pat. Nos. 3,068,776, 2,187,767, 3,195,441, 2,241,108, 3,368,756, 2,551,965, 3,436,016, 3,027,090, 3,528,606.
Above-mentioned U.S. Pat. No. 3,436,016 discloses a temperature responsive foundation ventilator construction having bimetallic spring operatively connected between fixed housing and movable shutters to provide for controlled movement thereof in response to predetermined temperature changes in the air passing through the shutter.
Although many such temperature responsive spring controlled louvered ventilators are known and used in the field of the art, there is the ever present need of providing a temperature responsive automatically controlled ventilator construction which can be more easily and economically manufactured with improved reliability of performance in use.